Ceiling Fan Downrod Length Calculator

With this ceiling fan downrod length calculator you can estimate the minimum and maximum size downrod needed for your ceiling fan. This can be used for a flat or sloped ceiling.

To see standard heights of light switches, outlets, and other things around the house, check out the standard heights calculator.

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ceiling fan diagram


How To Use This Calculator

First, make sure your fan blades will be at least 18″ from any wall.

Keep in mind if you have a light hanging below your fan and your ceiling is lower than 8′ you may not have enough head room.

Next, select whether you have a flat ceiling or a sloped cathedral ceiling.

If you have a flat ceiling, select the closest ceiling height where the fan will be anchored to and hit calculate.

Sloped Ceiling – Known Pitch

If you have a sloped ceiling and know the approximate slope of the ceiling, select “I know my ceiling pitch in degrees.”

Then, enter in your ceiling pitch in degrees.

After that, enter the radius of your fan in inches. Measure this from the center of the fan outwards to the tip of one of the blades.

Finally, enter the ceiling height where the fan will be anchored to and hit calculate.

Sloped Ceiling – Unknown Pitch

If you have a sloped ceiling but don’t know the pitch, you can take two measurements and enter them here to calculate the angle.

To do this, first select “I don’t know my ceiling pitch.”

Next, pick a spot on your ceiling to measure the rise and run. It is easiest to start where the wall meets the ceiling. Measure 12 inches over horizontally with one tape measure/ruler. Then, measure vertically from that point to the ceiling with another tape measure/ruler.

Enter 12 in the ceiling run box. Enter your vertical measurement in the ceiling rise box.

Finally, enter your fan radius and ceiling height where the fan will be anchored and hit calculate.

Ceiling Fan Downrod Tips

Distance from Walls

    • Fan blades should be at least 18″ from walls to allow maximum air flow. This also mitigates the chance of the fan swinging into the wall.

Minimum and Ideal Heights Above Floor

    • Fan blades are required to be a minimum of 7 feet above the floor. Ideally, they should be 8 to 9 feet above the floor for optimum air flow.
    • This ceiling fan downrod length calculator uses a blade height of 8 to 9 feet above the floor for most calculations. If you choose one of the lower ceiling heights or select the sloped ceiling option, a 7.5 foot blade height is used for the calculations to allow more flexibility.
    • For the purposes of this calculator, the downrod plus 6″ for the motor, etc. is equal to the total space between the fan blades and the ceiling anchor point

Downrods for Very Tall Ceilings

      • Downrods are usually sold in lengths of up 72″ at most hardware stores. If you have a ceiling height that requires a downrod longer than that, you can purchase a downrod extension like this one:

    Fan Blade Length

      • Size your ceiling fan according to the size of the room it will be used in. Here’s a great article on how to decide what size ceiling fan you need.

    Flush Mount Fans

      • Flush mount, or low profile fans like this one can be purchased for low ceilings. These do not have downrods. For the purposes of this calculator, assume there will be approximately 6″ between the ceiling and flush mount fan blades.

      Fans with lights

        • If your fan has a light below the blades, make sure to take this into account on low ceilings to allow enough headroom.